13-06-2012, 12:54 PM
An adaptive hysteresis band current controller for inverter base
DG with reactive power compensation
An adaptive hysteresis band current controller.pdf (Size: 926.92 KB / Downloads: 46)
Abstract
In this paper the three-phase grid connected
inverter has been investigated. The inverter’s
control strategy is based on the adaptive hysteresis
current controller. Inverter connects the DG
(distributed generation) source to the grid. The
main advantages of this method are constant
switching frequency, better current control, easy
filter design and less THD (total harmonic
distortion).
Introduction
Distributed energy offers solutions to many of the
nation's most pressing energy and electric power
problems, including blackouts and brownouts, energy
security concerns, power quality issues, tighter
emissions standards, transmission bottlenecks, and the
desire for greater control over energy costs [1].
Three-phase grid connected inverter
Three-phase inverters are widely used in industrial
applications such as motor drives, standby power
supplies and uninterruptible supplies. However in
three-phase grid connected inverter the output of the
inverter is connected to the grid. The inverter includes
six IGBT switches connected in the form of a bridge
configuration [7], [8].
Current control
Decoupled current control method has been used. The
goals are 1) injection of active power to grid and 2)
compensation of local load reactive power [2].
The three phase local load currents, which are shown
in Fig.2, already have been transformed to the
synchronous reference frame (a-b-c to d-q-0). The
coordinate transformation from three-phase local load
currents (iLa, iLb, iLc) to the synchronous reference
frame based local load currents (iLd, iLq, iL0) is obtained
as follows.
The adaptive hysteresis band
current controller
The hysteresis band current control technique has
proven to be most suitable for current controlled
voltage source inverters. The hysteresis band current
control is characterized by simplicity implementation,
inherent-peak current limiting capability, unconditioned
stability, very fast response, robust against system
parameters changing and good accuracy [5],[9].
However, the basic hysteresis technique exhibits also
several undesirable features; such as vary switching
frequency that causes acoustic noise and difficulty in
designing input filters [3].